Day lighting device

ABSTRACT

The present invention relates to an apparatus for collecting and transmitting sunlight into a space comprising a solar ray collecting device, a solar light transmitting device and a solar light emitting device, wherein said solar ray collecting device is arranged to collect sunlight and direct said sunlight to said solar light transmitting device, said solar ray transmitting device is arranged to transmit said sunlight from said solar ray collecting device into said space and to said solar light emitting device, and said solar light emitting device is arranged to emit solar light in said space. Said solar ray collecting device comprises at least one convex lens and at least one concave lens, and at least said convex lens or said concave lens is arranged to be movable in dependence of the angle of incident solar light so as to focus the solar light onto said solar light transmitting means through said convex and concave lens.

TECHNICAL FIELD

The present invention relates to collecting sunlight and transportingsaid sunlight into a space. More specifically, the present inventionrelates to an automatic sun tracking device and lens arrangement forcollection of sunlight for the purpose of illumination.

BACKGROUND OF THE INVENTION

To be able to introduce day light into a building has in all times beenof great interest. The human being has in all times, apart from themodern era with electric light, been dependent on the daylight and hasbiologically evolved under this constraint. The turning of the sunduring the day, from east to west, has a significant effect on peoplesperception of passed time, when to have different types of meals, whento sleep and when to get up, just to mention a few.

When designing buildings the introduction of daylight, in later timesparticularly through glass windows, is a major design consideration. Atthe same time, as land prices raise in popular areas, it is ofeconomical interest to build bigger buildings. These two requirementsare at times colliding. Residential blocks are most often not wider than9-10 meters. However, the wider buildings lack significant daylightcomfort. They tend to be somewhat like darker caves. A daylight sourceusing a daylight collector makes it possible to construct buildings withhigher utilization factor.

U.S. Pat. No. 5,022,736 “Solar ray device for illumination” discloses adevice comprising a solar ray collecting device having multiple opticallenses, and an illuminator connected through a plurality of lightguiding cables. The device further comprises a sensor for detecting thedirection of the sun's rays and for treating a control signal causingthe optical lenses to be directed toward the sun.

U.S. Pat. No. 4,297,000 “Solar lighting system” disclose a solarcollector device for directing solar light onto a bundle of opticalfibres. The device comprises a tracking system to direct to collectordevice towards the sun.

JP 591,602,14 “Solar light tracking device” disclose a solar trackingdevice for tracking to sun using a spring of a shape memory alloy.

U.S. Pat. No. 4,050,789 “Tracking lens system for solar collectors andskylights” disclose an arrangement for collecting solar light usingthree layers of lenses, a first condensing lens, a second diverging lensand a third condensing lens. More over the second lens need to bepositioned not only horizontally between the two condensing lenses butalso vertically to focus the beam correctly. These limitations requirethat sophisticated and expensive mechanism for moving the middle lens.It would be beneficial if fewer lenses could be used and if a movementin only two dimensions could be achieved.

U.S. Pat. No. 4,867,514 “Systems for deviating and (optionally)converging radiation” disclose a method for collecting solar lightcomprising first lens and second lenses. The second lens need to bemovable in direction to and fro said first lens to increase or decreasethe distance from the first lens as well as parallel to the first lensto collect the sun light. It would be beneficial if a movement in thedirection to and fro the first lens could be avoided to achieve asimpler and more cost effective solar collecting device.

SUMMARY OF THE INVENTION

It is a main object of the present invention to provide such apparatusand method that collects solar light in an efficient manner fortransmission into a space such as a building, a ship, a road tunnel, acave, a mine, a spacecraft or the like.

It is a specific object of the present invention to provide an apparatusand a method for collecting direct sunlight while allowing ambientsunlight into a building.

It is in this respect a particular object of the invention to providesuch apparatus and method that follows the movement of the sun over thesky using a low cost device comprising e.g. a memory alloy.

These objects among others are, according to a first aspect of thepresent invention, attained by a panel for mounting on a buildingcomprising a solar ray-collecting device. The solar ray collectingdevice is arranged to collect a substantial part of the direct sunlightfalling on said panel and direct said collected sunlight on a lighttransportation means or a light transformation means. The panel isfurther arranged to be substantially transparent to a substantial partof the indirect, or ambient, light so that said panel, when mounted on abuilding, allows ambient light into said building and collects directsun light falling on said panel.

By collecting the direct sunlight it can be transported to other partsof the building, or focused on a light-to-electricity converter. Bycollecting the direct sunlight it is also prevented to enter a room. Thepanel is thus functioning as a curtain or shader. The panel further moreallows ambient sunlight into the room, which thus is lit with acomfortable light, without the strong, direct sunlight.

According to a preferred embodiment of the first aspect of the inventionthe light transportation means is a light conducting fiber and/or thelight transformation means is a light to electricity conversion meanse.g. a fotodiod.

The panel comprises, in light propagation direction, a transparent topside and a transparent bottom side connected at the sides to form a box,said box encloses a lens arrangement for collecting direct sun light.

The box is thus substantially transparent to ambient sunlight butcollects, through the lens arrangement in the box, direct sunlight.

These objects among others are, according to a second aspect of thepresent invention, attained by an apparatus for collecting sunlighthaving a solar ray collecting device, comprising a first set of lensesarranged in arrays side by side to form a first sheet of lenses and asecond set of lenses arranged in arrays side by side to form a secondsheet of lenses. The apparatus further comprises means for moving saidfirst and second sheet of lenses in relation to each other only along asubstantially flat plane so that the distance between said first andsecond sheet is kept constant.

Movement along a substantially flat surface of the two lens sheets isparticularly easy to achieve. Thus, the means for moving the sheets inrelation to each other to follow the sun's movement and collect directsunlight may be a comparable simple design, which is cost effective,tolerant and will not require high maintenance.

According to a preferred embodiment of the first and second aspect ofthe present invention the lens arrangement comprises, in lightpropagating direction, first lenses arranged side by side having firstsubstantially planar surfaces and second convex surfaces and secondlenses arranged side by side having third concave surfaces and fourthsubstantially flat surfaces so that direct sun light passes first,second, third and fourth surfaces in said order. The first and secondlenses are displaceable in relation to each other in at least a firstdirection, but preferably in two orthogonal directions.

The design according to the invention assures a linearity of themovements in the system. This means that for every change in the angleof the incident light, within the angles that permit solar tracking,corresponds a proportional parallel movement of one sheet of lenses inrespect to the other in order to maintain the position of the focalpoint in its intended position.

According to another preferred embodiment of the invention the apparatusfor collecting and transmitting sunlight into a space comprising a solarlight transmitting device and a solar light emitting device, whereinsaid solar ray collecting device is arranged to collect sunlight anddirect said sunlight to said solar light transmitting device, said solarray transmitting device is arranged to transmit said sunlight from saidsolar ray collecting device into said space and to said solar lightemitting device, and said solar light emitting device is arranged toemit solar light in said space. At least one of said first and/or secondsheet is arranged to be movable in dependence of the angle of incidentsolar light so as to focus the solar light onto said solar lighttransmitting means through said convex and concave lens.

Thereby the collected sunlight can be used to lit a room inside abuilding.

According to another preferred embodiment of the invention the apparatuscomprises a displacing device wherein said displacing device comprisessolar ray sensitive means arranged to detect the position of the sun inthe sky and actuating means arranged to move said convex and/or concavelens in dependence of the detected sun position.

These objects among others are, according to a third aspect of thepresent invention, attained by a mechanical displacing device for movingan object, such as a lens, in dependence of the sun's position in thesky. The device comprises a solar ray shield having at least oneaperture, at least a first solar ray sensitive tongue, such as abi-metal or memory alloy tongue, arranged at least partly under said atleast one aperture in the direction of incident solar rays, and anactuator rod coupled to said solar ray sensitive tongue and arranged todisplace said solar ray shield and/or said solar ray sensitive tongue inrelation to each other in dependence of the incident angle of solarrays.

Thereby an effective, simple and low-cost device for moving the lensesaccording to the sun's position in the sky, to collect direct sunlightis achieved.

These objects among others are, according to a fourth aspect of thepresent invention, attained by a method for allowing light into abuilding including a solar ray collecting device, comprising the stepsof, mounting a panel having a substantially transparent outer surfaceand a substantially transparent inner surface on said building,collecting a substantial part of the direct sun light falling on saidpanel and directing said collected sun light on a light transportationmeans or a light transformation means, and allowing a substantial partof the indirect, or ambient, light to pass through said panel so thatsaid panel, when mounted on a building, allows ambient light into saidbuilding and collects direct sun light falling on said panel.

The invention can in general terms be described according to a preferredembodiment as a tracking lens system for dividing/separating direct andambient (indirect) sunlight. The direct sunlight is focused by a systemof lenses, while the ambient (indirect) sunlight passes the embodimenton the invention. The tracking lens system is suitable fog modificationof incident radiation, e.g. solar radiation. The modification of saidradiation is accomplished by having it pass two layers of opticaldevises. The main purpose is to produce a converging radiation in thespectrum of visible light from incident, substantially parallel sunlightwhere the converging radiation can be focused upon a collecting meansThis modification is possible for radiation, incident from differentangles in respect to the lenses, which is necessary to track the sun ifthe system is to be installed in a fix position on for example abuilding.

The object of the invention is to provide a system for tracking,collecting and modifying solar radiation. The principle is built upon apair of lenses but can be expanded to include an array of lenses mountedfor example in a panel. There are several possible applications of theinvention. An example is when combined with a transporting means such asoptical fibres. Then the system as a whole will enable collection ofsolar radiation as the sun passes from east to west and furthertransportation of said solar radiation to any chosen locations. Anotherexample is to focus the sunlight on photoelectric elements fortransformation of solar energy into electrical energy, either with saidphotoelectric elements in each focal point of the system or with aphotoelectric element placed in the focal point of a multiple of saidoptical fibres, thus achieving a great concentration of the sunlightReplacing these photoelectric elements with heat-conducting orheat-collecting elements, placed analogue as above said photoelectricelements results in yet another application, namely that of convertingthe solar energy into usable heat-energy.

The curvature of the plane-convex lens is designed to avoid totalinternal reflection within the invention's operating range.

The innovation can be scaled to generate focal point of different sizes.This can be useful for matching the size of an attached element, be itan optical fibre, a photoelectric elements or other element. Forinstance, photoelectrical elements may have an optimal size regardingperformance. The size of the focal point may thus be scaled to coincidewith the size of the photoelectrical element.

The pair of lenses can be designed so that a prismatic shape issuperpositioned either on the first convex lens or on the second concavelens or on both the first convex lens and on the second concave lens.The purpose of this is to produce a system with a greater operatingrange in either direction off from the normal axle, which isperpendicular to the pair of lenses and thus aiming the axle of the lenspair more in the direction of the incident, substantially parallelsunlight.

An advantage of the present invention is that a low cost device havingexcellent capabilities to collect sunlight is achieved. The device andmethod according to an embodiment of the present invention does moreover not comprise any expensive computerized parts which may needservice.

Further characteristics of the invention and advantages thereof will beevident from the following detailed description of embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description of embodiments of the present invention givenherein below and the accompanying FIGS. 1-16, which are given by way ofillustration only, and thus are not limitative of the present invention.

FIGS. 1 a and 1 b schematically shows a lens arrangement according to anembodiment of the invention in two different positions according to thesun's position in the sky.

FIG. 2 schematically shows a lens arrangement according to an embodimentof the invention.

FIG. 3 shows a perspective view of a lens arrangement displaceraccording to an embodiment of the invention.

FIGS. 4 a to 4 c schematically shows the displacer in FIG. 3 indifferent positions.

FIGS. 5 a and 5 b shows a top view of a displacer arrangement for movinga lens arrangement in two dimensions.

FIG. 6 shows a side view of the displacer in FIGS. 5 a and 5 b connectedto a lens arrangement.

FIGS. 7 a and 7 b shows a top and a side view of a sunlight collectingdevice according to an embodiment of the invention comprising amultitude of convex lenses.

FIGS. 8 a, 8 b and 8 c shows a bi-metal actuator according to anembodiment of the invention in three different positions.

FIG. 9 is a detail of the embodiment in FIG. 7 showing the couplingbetween the concave lenses, the optical fibres and the convex lenses.

FIG. 10 shows a schematic diagram of a sunray path through a lensarrangement.

FIG. 11 a to 11 e shows different arrangements of convex and concavelenses.

FIG. 12 is a detail of the embodiment in FIG. 7 showing the couplingbetween the bi-metal actuator and the arrangement of convex lenses.

FIG. 13 shows a schematic side view of a preferred embodiment accordingto the first aspect of the present invention, where direct sunlight iscollected into a light transportation means and ambient sunlight isallowed to pass through.

FIG. 14 shows a number of panels according to the first aspect of theinvention mounted on a building, allowing ambient light into a firstroom and collecting direct sunlight.

FIGS. 15 a to 15 c shows schematic side views of preferred embodimentsaccording to the present invention where prisms are used to change thepreferred angle of incident light.

FIG. 16 shows a perspective view of the arrangement in FIG. 13.

PARTICULAR EMBODIMENTS OF THE INVENTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particulartechniques and applications in order to provide a thorough understandingof the present invention. However, it will be apparent to one skilled inthe art that the present invention may be practiced in other embodimentsthat depart from these specific details. In other instances, detaileddescriptions of well-known methods and apparatuses are omitted so as notto obscure the description of the present invention with unnecessarydetails.

FIGS. 1 a and 1 b shows a lens arrangement according to an embodiment ofthe invention. A convex lens 101 is positioned above a concave lens 102in the line of incident light. The convex lens 101 and the concave lens10 cooperates to focus the incident sun light onto a light carryingmedia such as an optical fibre 103 for further guiding into a house.FIG. 1 a shows the lens arrangement when the sun is at its peek positionin the sky. In FIG. 1 b the sun's position in the sky has changed andthe sunlight has an angle in relation to the lens arrangement. To focusthe light onto the optical fibre 103 the convex lens 101 is displaced ascan be seen in FIG. 1 b.

FIG. 2 shows another embodiment of the lens arrangement. A convex lens201 is arranged above a concave lens 202 and both of said lenses 201 and202 cooperates to focus the incident light onto an optical fibre 203. Inthis embodiment both of the convex lens 201 and the concave lens 202 isdisplaced in relation to the optical fibre 203 when the sun's positionin the sky changes to continue to focus as much light as possible ontothe optical fibre 203.

FIG. 3 shows a blown perspective view of a displacer arrangement for usewith the lens arrangement in FIGS. 1 and 2. A lever 301 engages with afirst and second solar ray sensitive tongue denoted 302 and 303,respectively. The lever 301 also engages a pole 304 having engagingmeans 305. The pole 304 is arranged on a solar ray shield 306 having anaperture or window 307. As stated above, the first and second tongue 302and 303 respectively is in a first end engaging said lever 301 and is inthe other end fixed to a bottom plate 308. The solar ray shield 306 ismovably secured to the bottom plate 308 so that it is displaceable in atleast one direction.

The solar ray shield is arranged so that solar light passing throughsaid window 307 will fall upon the first and second tongue 302 and 303,respectively. In dependence of the sun's position in the sky differentparts of the tongues 302 and 303 will be reached by the incident light.The tongues 302 and 303 are of a solar ray sensitive material forinstance a heat sensitive metal such as a memory alloy or a bimetal andis arranged to bend in vertical direction in dependence of the amount ofsunlight reaching respective tongue. When the respective tongue moves upor down they will engage the lever 301 which in turn will engage thepole 304 and displace the shield 306. Thus the shield will be displacedin dependence of the sun's position in the sky. This will he furtherexplained below with reference to FIG. 4.

FIGS. 4 a to 4 c shows in a front view the principles behind themovement of the sunray shield 306 in FIG. 3. The sun's position in thesky and the angle of incident light is schematically shown and isdenoted 401. In FIG. 4 a the sun is in its peek position and the sunraysis failing straight through the window 307 at the tongues 302 and 303,respectively. In FIG. 4 b the sun has moved over the sky and the raysare not longer falling in straight through the window 307 but ratherwith a slight angle. This means that the projection of the window hasmoved over the tongues 302 and 303, respectively as can be seen in FIG.4 b. Thus tongue 302 gets warmer and tongue 303 cools off, which in turnresults in that the tongue 302 bends slightly upwards and tongue 303bends slightly downwards as can be seen in FIG. 4 c. The tongues engagethe lever 301 and tilt the lever, which in turn engages the shield 305and moves the shield 306. Thus the window 307 is moved and theprojection of the window 307 on the tongues 302 and 303 is moved untilequilibrium is achieved.

The sun's position in the sky depends in one direction, namely eastwest, of the time of the day and in another direction, namely heightover the horizon, of the day of the year. This latter direction isspecifically accentuated the farther from the equator the sun collectoris positioned. To also consider the sun's height over the horizon thedisplacer previously discussed need to be modified to be able todisplace the lens arrangement in two dimensions. The principles remain,however the same.

FIGS. 5 a and 5 b shows a two dimensional displacer according to anembodiment of the invention. FIG. 5 a shows, in a top view, a disc 501having four solar ray sensitive, e.g. heat sensitive, tongues denoted502, 503, 504, 505, respectively. The tongues are arranged to bend up ordown depending on the amount of sunlight reaching each tongue. FIG. 5 bshows a top view of a solar ray shield 506 having four apertures orwindows denoted 507, 508, 509, 510, respectively. The shield 506 is tobe arranged above the disc 501 as can be seen in FIG. 6.

FIG. 6 shows a schematic side view of a two dimensional displaceraccording to an embodiment of the invention having a lens arrangementand employing the disc and shield shown in FIGS. 5 a and 5 b. Likedetails are denoted with same numerals. The shield 506 is arranged abovethe disc 501. The tongues engage a lever 601, which transmutes themovement of the tongues into a movement of the disc 501. At the edges ofthe disc 501 is a lens arrangement 602 arranged and schematically shown.Thus, the movement of the tongues is transmitted to movement of the lensarrangement 602.

FIG. 7 a shows a part of a sunlight collecting arrangement 700comprising a multitude of convex lenses 701 in top view according to anembodiment of the invention having several bi-metal actuators 702arranged on each side. The sunlight collecting arrangement comprises atop plate 703 and a bottom plate 704 arranged in a box 705 havingtransparent top and sides. The bottom plate 704 comprises concave lensesfocusing the collected sunlight into optical fibers for transmission toan illumination arrangement (not shown). The top plate 703 comprises theconvex lenses 701 and is movably arranged in relation to the bottomplate 704 as will be described in greater detail below. FIG. 7 b showsthe arrangement in FIG. 7 a in side view.

Sunliqht collecting panels, such as the arrangement shown in FIG. 7 canbe used on roofs, on the facings of a building, on noise protections atroads etc. They may even be visually usable as means of expression inarchitecture. The panels could for instance be made semitransparent andbe used as protection against direct sunlight, which is directed awayinto light transmission fibers, but let through indirect sunlight forillumination purpose.

The panels could also be used for animations, information andcommercials. If the panel is viewed from the top side 703 a very muchenlarged picture of the bottom plate 704 is seen. If the bottom plate iscolored with dots in a repetitive pattern the color of the panel willchange as the viewer change position in relation to the panel. If thepanel is viewed from a fixed point the panel will change color dependingon the position of the sun depending on that the top plate 703 followsthe movement of the sun. By skillfully selecting the color and positionof the dots on the bottom plate 704 a moving viewer, such as onetraveling by car, would get the impression of for instance an animation.If the panel is designed in a semitransparent material it could be litat night to display its message.

The size of the panels can be between 50 mm, and 3000 mm preferably 600mm. They can be hexagonal with the distance between opposite parallelsides between 50 mm and 3000 mm, preferably 600 mm. If the panels arerectangular they may have sides up to 2 meters and down to 50 mm. Thethicknesses of the panels are manly depending on the focal distance andsize of the lenses, possibly between 5 mm and 300 mm, preferably 30 mm.To be able to completely cover a surface, “dummy” panels of similarstructure and color can be used, which do not collect sunlight butotherwise look like a sunlight collecting panel.

FIGS. 8 a to 8 c shows bi-metal actuator 702 in three differentconfigurations. The actuator 702 is affected by the incident sunlightand a bi-metal tongue 801 change position in dependence of said incidentsunlight as can be seen in the figures. The tongue 801 is coupled to thebottom plate 704 and a coupling means 802 is coupled to the top plate703, as will be described in more detail below. Thus, when the tonguechange position the relative position between the top and bottom plates703 and 704 will also change.

FIG. 9 shows an enlarged detail of FIG. 7. The coupling between the topplate 703 and the bottom plate 709 is partly arranged by the bi-metalactuators 702 and partly by a number of rods 901. The rods 901 arearranged in conical recesses in the bottom plate 704 and between theconvex lenses 701 in the top plate 703. As can be seen the top plate 703will have a two dimensional freedom of movement along a sphericalsurface. In FIG. 9 also the concave lenses are shown 902 as well asoptical fibers 903 detailed in relation to FIG. 10.

FIG. 10 shows a schematic diagram over the sun ray oath through theconvex lens 701, the concave lens 902 to a reflective surface 1001 andin to the light carrying optical fiber 903 for further transmission to alight emitting device (not shown). The reflective surface may be planaror may be somewhat curved to reflect the light into the optical fiber903. The presence of the reflective surface allows for design of athinner panel.

FIG. 11 a to 11 c shows 2 lens arrangement suitable when the sunlightcollection arrangement 700 is horizontally positioned and the sun is inzenith. However, it might be beneficial to position the collectionarrangement 700 on a roof with an angle to the horizontal plane or evenon a wall substantially vertically. Then the sunlight will have an angleof incidence, which need to be considered. FIGS. 11 d and 11 e shows alens arrangement suitable for an arrangement where the collectionarrangement 700 is positioned with an angle in relation to thehorizontal plane. As can be seen the arrangement in FIGS. 11 d canhandle light with a greater angle of incidence. Preferably the sunlightcollection arrangements 700 may be manufactured in a couple of differentconfigurations suitable for placement with different angles in relationto the horizontal plane, for instance 0 degrees, 35 degrees, 70 degreesand 90 degrees. The angles may be selected to agree with common roofangles for the specific market.

FIG. 12 shows an enlarged portion of the embodiment depicted in FIG. 7in greater detail. A extending portion 1201 of the bi-metal actuator 702comprises a friction reducing means 1202, such as a roller, bearing orthe like, which is situated in a recess 1203 in the top plane 703. Sincethe top plane 703 moves along a spherical surface, as described earlier,the top plane 703 will move slightly up and down when the bi-metalactuator 702 moves the ton plane 703. Hence, the recess 1203 is deepenough to allow for the extending portion 1201 during the completemovement. The friction reducing means 1202 may comprise rollers in bothvertical and horizontal direction even though only horizontal is shownin the figure.

FIG. 13 shows a part of a first sheet of lenses 1301 and a part of asecond sheet of lenses 1302 with the first sheet 1301 arranged above thesecond sheet 1302. The second sheet 1302 of lenses is movable in adirection A to collect direct 1303 sunlight and focus said directsunlight on light transportation means, in this embodiment fibers 1304.Ambient, or indirect light is schematically shown in FIG. 13 with dottedlines, and as can be seen in the figure is allowed to pass through thearrangement.

Each lens 1305 in the first sheet of tenses 1301 comprises a firstsubstantially flat surface 1306 and a second convex surface 1307. Eachlens 1308 in the second sheet of lenses 1302 comprises a third concavesurface 1309 and a fourth substantially flat surface 1310. The twosheets together form a light propagation arrangement, which isspecifically suitable to collect direct sunlight and focus said light ona specific position or point 1311. The arrangement need not adjust thespacing between the two sheets 1301 and 1302. The collected light isfocused on points 1311 on the plate 1312 which is fixed relative thesecond sheet of lenses. Thereby, the sheets of lenses 1301 and 1302 onlyneed to be movable along a flat plane in relation to each other.

FIG. 14 shows a schematic drawing of panels 1403, comprising the lensarrangement disclosed in FIG. 13, mounted on a roof or facade or as apart of a roof or facade or as a sunshield 140l on a building 1402.Direct sunlight is shown with straight arrow lines and ambient light isshown with dotted arrow lines. The panels 1403 collect direct sunlight,which is transported through fibers 1404 to light emitting devices 1405located in inner rooms 1406 in the building 1402. Ambient light passesthrough the panels 1403 into the room 1407, which thus is lit with acomfortable natural light.

FIGS. 15 a to 15 c schematically shows different embodiments accordingto the present invention involving prisms to increase the preferredangle of incident sunlight. The embodiment without prisms would showbest performance if positioned perpendicular to the incident directsunlight. That is on the equator directly flat on the ground and onother latitudes with a corresponding angle to the ground. If positionedotherwise the direct sunlight do not fall perpendicular on the lensarrangement reducing the performance of the apparatus. To counteractthis prisms, or functionally equal elements, are incorporated into thearrangement.

FIG. 15 a shows a first sheet of lenses 1501 where each lens comprises aprism part 1502 to refract the incident sunlight so when the incidentsunlight reaches the first surface 1503, indicated with dotted lines, itis in fact perpendicular to said surface. The prism part 1502 isactually a part of the lens 1501 and is not a separate item.

FIG. 15 b shows the prisms located on the second sheet of lenses 1504 torefract the sunlight coming out from the fourth surface 1505, indicatedwith dotted lines, on the collection points 1506.

FIG. 15 c shows two sets of prisms on the lower concave lens to improvethe efficiency in certain situations and to further increase theeffective receiving angle for incident light.

FIG. 16 shows a perspective view of the inventive arrangement disclosedin FIG. 13.

It will be obvious that the invention may be varied in a plurality ofways. Such variations are not to be regarded as a departure from thescope of the invention. All such modifications as would be obvious toone skilled in the art are intended to be included within the scope ofthe appended Claims.

1. A panel for mounting on a building comprising a solar ray collectingdevice, said panel is further arranged to be substantially transparentto a substantial part of the indirect, or ambient, light so that saidpanel, when mounted on a building, allows ambient light into saidbuilding and collects direct sun light falling on said panel, said solarray collecting device is arranged to collect a substantial part of thedirect sun light falling on said panel and direct said collected sunlight on a light transportation means or a light transformation means,said solar ray collecting device is a lens arrangement having opticallenses for focusing said direct sunlight onto said light transportationmeans or light transformation means, and wherein said lenses in saidlens arrangement is provided to allow ambient daylight to pass saidpanel to lit a space in said building with a natural light, wherein,said lens arrangement comprises, in light propagating direction, firstlenses arranged side by side having first substantially planar surfacesand second convex surfaces, second lenses arranged side by side havingthird concave surfaces and fourth substantially flat surfaces so thatdirect sunlight passes first, second, third and fourth surfaces in saidorder, and said first and second lenses are displaceable in relation toeach other in at least a first direction.
 2. The panel according toclaim 1, wherein said light transportation means is a light conductingfiber.
 3. The panel according to claim 1, wherein said lighttransformation means is a light to electricity conversion means e.g. afotodiod.
 4. The panel according to claim 1, wherein said panelcomprises, in light propagation direction, a transparent top side and atransparent bottom side connected at the sides to form a box, said boxencloses a lens arrangement for collecting direct sun light.
 5. Thepanel according to claim 1, wherein at least one of said first and/orsecond lenses are displaceable along a straight plane parallel to saidtop and bottom sides.
 6. An apparatus for collecting sunlight having asolar ray collecting device, comprising a first set of lenses arrangedin arrays side by side to form a first sheet of lenses, a second set oflenses arranged in arrays side by side to form a second sheet of lenses,means for moving said first and second sheet of lenses in relation toeach other, said first and second sheet of lenses is movable withrelation to each other substantially only along a substantially flatplane so that the distance between said first and second sheet is keptconstant to thereby focus said sunlight onto a light transportationmeans or a light transformation means, wherein each of said lens in saidfirst set of lenses comprises a first substantially flat surface and asecond convex surface, each of said lens in said second set of lensescomprises a third concave surface and a fourth substantially flatsurface, and incident light passes through said lens arrangement throughsaid first, second, third and fourth surface in that order.
 7. Theapparatus according to claim 6 for collecting and transmitting sunlightinto a space comprising a solar light transmitting device and a solarlight emitting device, wherein said solar ray collecting device isarranged to collect sunlight and direct said sunlight to said solarlight transmitting device, said solar ray transmitting device isarranged to transmit said sunlight from said solar ray collecting deviceinto said space and to said solar light emitting device, and said solarlight emitting device is arranged to emit solar light in said space,wherein at least one of said first and/or second sheet is arranged to bemovable in dependence of the angle of incident solar light so as tofocus the solar light onto said solar light transmitting means throughsaid convex and concave lens.
 8. The apparatus according to claim 6,wherein said first and/or second sheet is movable in a first directioncorresponding to the direction of the sun's movement over the sky duringa day.
 9. The apparatus according to claim 6, wherein said first and/orsecond sheet is movable in a second direction corresponding to the sun'sheight over the horizon.
 10. The apparatus according to claim 6, whereinsaid movement of said first and/or second sheet is achieved through adisplacing device wherein said displacing device comprises solar raysensitive means arranged to detect the position of the sun in the skyand actuating means arranged to move said convex and/or concave lens independence of the detected sun position.
 11. The apparatus according toclaim 10, wherein said actuating means is an electric motor.
 12. Amechanical displacing device for moving an object, such as a lens, independence of the sun's position in the sky, comprising, a solar rayshield having at least one aperture, at least a first solar raysensitive tongue, such as a bimetal or memory alloy tongue, arranged atleast partly under said at least one aperture in the direction ofincident solar rays, an actuator rod coupled to said solar ray sensitivetongue and arranged to displace said solar ray shield and/or said solarray sensitive tongue in relation to each other in dependence of theincident angle of solar rays.
 13. The mechanical displacing deviceaccording to claim 12, wherein said displacing device comprises at leasttwo solar ray sensitive tongues arranged parallel with each other undersaid aperture in the direction of incident solar light, said at leasttwo solar ray sensitive tongues are coupled to said actuator rod so asto force said actuator rod to move said solar ray shield and/or said atleast two solar ray tongues in relation to each other to achieve anequilibrium.
 14. The mechanical displacing device according to claim 12,wherein said actuator rod is arranged to displace said solar ray shieldand/or said at least two solar ray tongues in relation to each other ina east-west direction.
 15. The mechanical displacing device according toclaim 12, wherein said actuator rod is arranged to displace said solarray shield and/or said at least two solar ray tongues in relation toeach other in a south-north direction.
 16. The mechanical displacingdevice according to claim 15, wherein said displacing device comprisesfour solar ray sensitive tongues coupled to said actuator rod so as toforce said actuator rod to move said solar ray shield and/or said foursolar ray tongues in relation to each other in a first and a seconddirection.
 17. (canceled)